Not a silly question at all theres quite a few of them, it reallty depends on what operating system you use ie Win 98, ME or XP and what sort of gamepad do you want and how much do you wish to spend. As an example click here
PS the reason I mention operating system is, before you buy anything make sure if you use an older operating system that it is compatible with it. Some of the newest hardware can be Windows XP only so read before you buy.
Have a look here as well click here I can also recommend Microsoft ones and Logitech ones Saitek are also meant to be good but I've never had one. Don't buy the cheap unbranded ones as they are rubbish.